Image sensor with auxiliary light source

Abstract

An image sensor comprising at least one first light emitting element for irradiating an original with light, at least one photoconductive element for sensing the light via the original and at least one second light emitting element for irradiating the photoconductive element with light. The second light emitting element emits light of photoenergy smaller than the optical band gap of the photoconductive element.

What we claim is: 
     
       1. An image sensor comprising: at least one first light emitting element for irradiating an original with light;   at least one photoconductive element for sensing the light from said first light emitting element via the original, said photoconductive element being positioned on a surface of a transparent insulating support at a side opposing the original and having a transparent protection layer at a side on which the light from said first light emitting element via said original is incident; and   a second light emitting element for irradiating said photoconductive element solely with light having a photoenergy smaller than an optical band gap of of a semiconductor layer of said photoconductive element,   said transparent insulating support having a light shielding layer cutting off the light from said first light emitting element but transmitting the light from said second light emitting element, and a slit through which the light from said first light emitting element can pass.   
     
     
       2. An image sensor according to claim 1, wherein said photoconductive element includes an amorphous semiconductor layer. 
     
     
       3. An image sensor according to claim 2, wherein said amorphous semiconductor layer is made of amorphous silicon. 
     
     
       4. An image sensor according to claim 1, wherein said first light emitting element is an array of LEDs. 
     
     
       5. An image sensor according to claim 1, wherein said second light emitting element is an array of LEDs.